United States: Water deficits forecast MO, LA, & Mid-Atlantic States

29 January 2018

THE BIG PICTURE

The 12-month forecast indicates widespread water deficits of varying severity across much of the southern two-thirds of the nation, reaching from California to Maryland. Significant deficits – severe to exceptional – are expected to be particularly pervasive in California, southeastern Missouri, Arkansas, Louisiana, Mississippi, and central North Carolina. Some deficits, primarily moderate, are also forecast for northwestern Minnesota and trailing through the Northeast from Pennsylvania through Massachusetts. Conditions in the Ohio River Valley are forecast to be relatively normal. Primarily moderate surpluses are forecast for northern Idaho, western Montana, northwestern Wyoming, northeastern Nebraska, southwestern Minnesota, southwestern Michigan, and western New York.

Outside the contiguous US, surpluses are forecast for western Alaska and deficits in the east; intense surpluses are forecast for the island of Hawai’i; and, deficits are expected in western Puerto Rico.

IMPACTS
Heavy rainfall in Southern California's Santa Barbara County on January 9th created a massive mudslide that left at least 21 people dead and swamped Highway 101. The mud carried debris, houses, cars, and boulders along a vast, scorched path left by the Thomas Fire in December - the largest wildfire in the state's history.

A so-called “bomb cyclone” hit the eastern United States in early January, dealing high winds and up to two feet of snow. The blizzard magnified a king tide, creating a record high water level of 15.16 feet in Boston which flooded the city and other New England coastal towns with freezing seawater. A drastic cold snap followed, surging demand for natural gas. Prices spiked sixty-fold, promoting the import of Russian liquefied natural gas into Boston from the UK. Arctic air extended to the American South causing “lizard blizzards,” in which stunned iguanas fell from trees and scattered the backyards of Florida residents. The Texas National Park Service rescued dozens of cold-stunned, floating sea turtles from the chilly Gulf of Mexico.

While the East continues to be blanketed, the West would welcome more of the white stuff. Lack of snowfall has hurt ski resorts in Colorado, Utah, and New Mexico this season, though conditions improved somewhat in northern Colorado after a snowstorm in late January. Since shortly after Thanksgiving, one resort in Colorado has financed a soup kitchen for its underemployed seasonal employees. In Santa Fe, only 7 inches of snowfall was recorded as of early January, making the seasonal average of 225 inches an unlikely target.

Though it is still too early to predict impacts, officials in California are closely monitoring Sierra snowpack, the source of one-third of the state's water supply. As of 22 January, the Department of Water Resources estimated statewide snowpack at merely 23 percent of normal.

FORECAST BREAKDOWN
The 3-month maps (below) show the evolving conditions in more detail.

The near-term forecast – January through March – shows significant relief in the Southwest and Southern California from widespread exceptional deficits observed during the prior three months, as deficits moderate overall. Deficits will continue to emerge in Central California and from the Bay Area to Sacramento, including pockets of exceptional deficit. Intense deficits will spread in Missouri and across the border into western Illinois, persist in northern Louisiana and central Mississippi into central Alabama, and emerge in central North Carolina, much of Virginia, Maryland, and Delaware. A slight uptick in the extent and intensity of deficits in North Dakota and northwestern Minnesota is expected.

Normal water conditions are forecast for the Ohio River Valley, and relatively normal conditions for much of the Northeast. Intense surpluses will continue to emerge in central Nebraska, central Minnesota, and eastern Idaho. Surpluses of generally lesser intensity are forecast for western Montana, northern Idaho, southern Wyoming, northeastern Minnesota into Wisconsin, and Michigan. In Florida, a transition is forecast from surplus to moderate deficit.

From April through June moderate to severe deficits are forecast across the southern US from California to North Carolina, with severe to extreme deficits in northern Louisiana into southern Arkansas and western Mississippi. Conditions from Virginia through Delaware are expected to return to near normal or mild surplus, as will conditions in Missouri and western Illinois. Deficits in North Carolina will moderate. Surpluses will emerge in greater extent in northern Idaho, Oregon, western Montana, northwestern Wyoming, and moderate surpluses will emerge along the Columbia, Missouri, and Yellowstone Rivers. Surpluses could reach exceptional intensity in northwestern Wyoming and a pocket in west-central Idaho. Mild deficits will begin to emerge in the Northeast.

The forecast for the final months – July through September – indicates deficits in the West, Deep South, and Southeast.

(It should be noted that forecast skill declines with longer lead times.)

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.